Blind end cylinder honing machine



F b. 15, 1938. F, A. SWANSON 2 8,354 v BLIND END CYLINDER HONING MACHINEFiled June 8, 1955 2 Sheets-Sheet 1 NVENTOQJ QATTOIQIjEEjS Feb. 15,1938. F, A. swANsoN BLIND END CYLINDER HONING MACHINE Filed June 8, 19352 Sheets-Sheet 2 NVENTOIQ/ Patented Feb. 15, 1938 PATENT -OFFlCE amass;nnmn nun crmvnna HONING moms Floyd A. Swanson,

Rockford, Ill., asslgnor to Barnes Drill (30., Rockford, 111., acorporation of Illinois Application June a, 1935, Serial No. 25,546 vThis invention relates to an improved honing machine and in, particularto a machine of this character for finishing the interior walls ofcy'linders having one end closed or obstructed. such.

and overruns the ends, as in an ordinary auto- 10 mobile engine block,the metal removing effect of the tool is uniform because at every strokecontact is had throughout the length of the tool identically with everypart of the cylinder wall. When honing an obstructed or blind endcylinder, however, the stroking movement of the tool must be stoppedshort of the-obstructed end and in consequence the parts of the cylinderwall adjacent this end do not receive the benefit of treatment from thewhole length of the tool as do the remaining parts of the wall. That is,the same amount of metal per unit area is not removed throughout thebore because the longitudinal movement ofthe grinding stones of thehoning tool in contact with the inner end of the cylinder wall isnecessarily restricted and the tool therelength of time with this partof the wall as with the'remaining parts. Correction of this condition bycausing the tool to operate equally upon 30 every part of the cylinderwall is of great importance because of the requisite for uniformity inpiston operated mechanisms such as airplane engines and the like. In aradial airplane engine the blind end of the cylinder is that which forms.35 the cylinder head, and the piston of such an engine must closelyapproach the head in order to develop the necessary compression foroperation. It is clear, therefore, that in order to obtain properresults from the engine, and topre- 40 vent excessive wear on thepiston, the cylinder wall .throughout'must be as nearly perfect inuniformity of diameter andfinishas possible.

An important object of the present invention, therefore, is to provide ablind end cylinderhoning machine embodying a reciprocating, rotary tooland having control means for the tool operative to compensate for thenecessarily restricted stroking movement of the tool along the areaadjacent the blind end of the bore so that 5 the metal removed per unitarea from the bore wall will be substantially equal throughout.

Another object resides in the provision of an improved honing machinefor finishing the bores of blind end cylinders including a work supportand a tool support carrying a honing tool rofore is not in operativecontact for the same tating at constant speed with means for imparting.rapid reciprocatory movements to one of said supports through apredetermined range and arranged to vary the rate of relativereciprocation at one end of said range. 5

Another object is to provide a honing machine in'which a honing toolrotated at a constant speed isarranged for reciprocation relative to awork piece having an obstructed or blind end cylindrical bore, therebycarrying the tool through a predetermined range overrunning the free endof the'bore and closely approaching the blind end, and having automaticcontrol means for interrupting reciprocal movement of the tool for apredetermined interval while the same is near said blind end so that thetool will be in metalremoving contact with the cylinder wall adjacentthis end for a substantially equal length of time as with the remainderof the wall.

Another object is to provide a honing tool of the foregoing character inwhich the automatic control means is adjustable through a substantialrange to vary the period of delay in the reciprocal operating cycle andthus the length of time the honing tool will be in metal-removingcontact with the wall of the cylinder adjacent the obstructed"- partthereof.

A more detailed object resides in the provision in a honing machine,embodying a hydraulically reciprocated honing tool, of a delayed actionvalve arranged in conjunction with the main control valve of thehydraulic circuitof the machine to delay the return movement of thereciprocal stroke of the tool, and manually adjustable to any one of aplurality of operative positions accurately determinative of the periodof delay.

Another object resides in the provision. in a honing machine including areciprocating rotary honing tool of improved adjustable positive depthstop means for preventing movement of the tool beyond a predeterminedpoint short of the blind end of a cylindrical bore, and means forcushion? ing operation of the stop means so as to prevent jarring ofthe. machine.

Other objects and advantages will become apparent from the followingdescription taken in connection with the accompanying drawings, inwhich:

Figure 1 is a perspective view of a honing machine embodying theprinciples of the invention.

Fig. 2 is a schematic representation of the hydraulic operating meansand the delayed action control means.-

Fig. 3 is an enlarged sectional view of the delayed action valve.

Fig. 4 is an enlarged fragmentary sectional view taken substantiallyalong line 4-4 of Fig. 3.

Fig. 5 is an enlarged fragmental elevational view partially in section,of the tool-carrying spindle and the stop cross arm which is carriedthereby.

The invention has been successfully embodied in a honing machine of thegeneral type illustrated in Fig. 1, and adapted for honing to asubstantially uniform, smooth and highly finished surface, the internalcylindrical walls of obstructed bores of the character employed in suchmachinery as certain compressors or of blind end cylinders such asencountered in radial aircraft motors and the like. The machine selectedfor purposes of illustration, is of the vertical type embodying a basel0 carrying .a column or standard l2, near the lower end of which is anadjustable work support 13 upon which the work piece to be honed may bemounted in the usual manner. Vertically supported from the upper end ofthe column I 2- is a stationary tool head indicated generally at l4 andsupported on one side of the column overlying the work support I3. Themeans for performing the actual honing operation comprises in thepresent instance a single honing tool I5 of any preferred type carriedupon the lower end of a rotatable spindle I! which is suitably journaledin the tool head l4 and reciprocated relative to the work support'l3 soas to move the honing tool into and out of the cylinder bore of the workpiece.

In the preferred embodiment of the invention the honing tool iscontinuously rotated during the honing operation at apredetermined'constant speed, and to this end the spindle I1 is providedwith a splined section l8 operatively associated with a beveled crowngear l9, mounted on a fixed axis within a gear housing 20, and formingpart of a gear train (not shown) of well known type operated by anelectrical motor 22. Suitable clutch mechanism (not shown) is suppliedfor controlling operation of the gear train, and means such as amanually operated lever 23 is mounted on one side of the column l2 andhas a linkage connection 24 for actuating the clutch mechal'llSm.

In the present instance reciprocal motion is imparted to the toolspindle I! by hydraulic means including a cylinder 25 convenientlymounted upon the upper end of the tool head 14 and having therein areciprocating piston 21 which is secured upon the upper end of thespindle. The piston 21 is caused to reciprocate by alternatelyintroducing pressure fluid to opposite sides thereof, the means foraccomplishing this being shown (Fig. 2) as including an upperpressure-fluid delivery line 28 connected with the 'upper end of thecylinder, 25 for delivering pressure fluid to cause downward motion ofthe piston 21, and a lower pressureefluid delivery line 29 connectedwith the lower end of the cylinder for delivering fluid to cause returnmovement of the piston.

Pressure fluid is delivered to the lines 28 and 29 through a feed line30, one end of which is disposed for withdrawing the fluid from areservoir 32. Asuitable pump 33 in the line 3!! creates the necessaryfluid pressure.

and to this end a direction control valve 34 spective pressure fluidlines. This control valve The flow of pressurefiuid from the line 30 iscontrolled to pass only .to one of the delivery lines 28 or 29 at atime;

may be of the type embodying a cylinder carrying a reciprocal plunger 35having a pair of spaced full diameter portions 31 and 38 movablerelative to the outlet ports of the pressure fluid delivery lines 28 and29, respectively, and so arranged that the line 30 discharges betweenthe same in any position of the plunger. Thus, as the plunger 35 isreciprocated, the pressure fluid delivered by the line 30 will bealternately delivered to that delivery line of which the outlet isbetween the enlarged diameter portions 31 and 38. As the pressure fluidis delivered to one side of the piston 21 through one of the lines 28and 29, the fluid on the opposite side of the piston is exhaustedthrough the other line and passes through the control valve for returnto the reservoir 32 through a return line 39.

In order to prevent the building up of excessive pressure in thecylinder 25 while the machine is inactive, a cut-out valve 40 is placedat a suitable point in the feed line 30 for diverting the stream ofpressure fluid to the return conduit 39 in the periods betweenoperations. Control of the cut-out valve 49 is effected through theoperating lever 23 which may be connected thereto by suitable means suchas a linkage system 4| so that the delivery of pressure forreciprocating the spindle I! will be coordinated with operation of therotary drive clutch mechanism. Operation of the direction control valve34 is effected automatically in the present instance through anauxiliary hydraulic circuit adapted to shift the plunger 35 coordinatelywith the attainment of upper and lower limits of the reciprocal range ofthe tool spindle H. In the present instance this auxiliary hydrauliccircuit includes a line 42 connected with one end of the valve 34 and aline 43 connected with the other end of the valve, both of these lineshaving connection through a pilot valve 44 with a line 45 branching fromthe pressure fluid delivery line 30. The ends of the plunger 35 carryprojecting pistons 41 and 48 fitting slidably in auxiliary cylinders 49and 50, respectively, at the opposite ends of the valve casing. It willbe seen, therefore, that as the pilot valve 44 completes a pressurefluid connection between either of the lines 42 or 43 and the branchline 45, pressure fluid will be delivered to the respective cylinder 49or 50 to move the'plunger 35.

, Automatic operation of the pilot valve 44 is attained through themedium of means such as longitudinally movable and manually rotatableskip-stop'mechanism 5| connected with the pilot valve 44 and having anadjustable upper limit stop 52, an adjustable skip-stop 53 and a lowerlimit stop 54. A stroking arm 55 connected with the tool spindle ispositioned to engage the stops at predetermined points in the reciprocalcycle. It will be seen, therefore, that as the spindle moves the arm 55away from the stop 52 to approach the work the arm passes the skip-stop53 and proceeds into the cylinder bore to the lowermost limit of thereciprocal cycle. Thereupon, the stop 54 is engaged to move theskip-stop mechanism and shift the pilot valve. Upward movementof thespindle is limited at a point short of withdrawing the tool entirelyfrom the bore by engagement of the stroking arm with the stop 53 andreversal of the reciprocal cycle. Reciprocation of the spindle, throughthis arrangement, is continuous until the machine is halted by movementof the lever 23 :or otherwise. The length of the reciprocal stroke ofthe spindle and tool is accurately defined by the spacing By the presentinvention, uniformity of result in honing blind end cylinders isobtained by halting the honing tool positively at a predetermined pointwithin the cylinder as close to the blind end thereof as possible; andby the provision of means for automatically causing a carefullycalculated delay in the transition from the.

downward or approaching to the return reciprocal strokes of the tool. Bythus increasing the duration of contact of the rotating tool with theeffected part of the cylinder wall, enough metal is removed per unitarea to compensate for any deficiency in thisfspect resulting fromthenecessarily restricted longitudinal movement of the tool in engagementwith the wall. In Fig. 2 a blind end aircraft cylinder 51 is shown asthe work piece being honed, and the hone I5 is in the limit positionmost closely approaching the blind end where compensating metal removalis effected.

Insertion of the honing tool is accurately limited at a given point nearthe blind end of the cylinder bore through cooperatively arranged meanson the stationary tool head 14 and the spindle II. To this endabutmentshoulders 58 'on the tool head are arranged on opposite sides.

of the spindle axis, and a cross arm 59 for engagement with theshoulders is attached rigidly to the spindle at a point on its lengthwhich will cause the same to be halted positively at the predeterminedextreme limit of the downward stroke of the spindle. As best seen inFig. 5,

the spindle l1 may be in two sections, having its upper section'coactingrigidly with the cross arm and having the lower section coupled forrelative rotary movement. In a preferred construction. the upper end ofthe lower section of the spindle may carry a fixedly pinned flange l'lwhich is .interposed between suitable antifriction means such asbearings 11 The bearings may be supported within a housing 59 boltedsecurely to the lower side of the cross arm 59. In. this manner theentire spindle may be reciprocated freely but only the lower sectionthereof which carries the honing tool need be rotated:

Preferably the cross arm 59 has a pair of similar portions extending toopposite sides of the spindle and extending through slots 60 in the toolhead. The cross arm may be adjustable bodily relative to thespindle,-and is shown as having adjustable screw abutments 62 forminutely adjusting approach of the arm relative to the shoulders 58 toeffect minor variations in stroke length. Desirably, the stroking arm 55may form an extension of one branch of the cross arm 59.

The means forcausing the tool l5.to dwell near an internal obstructionor at the blind end of the cylinder, forms part of the auxiliaryhydraulic circuit which operates the control valve 34. As shown, it isarranged to delay shifting of the plunger 35 for initiating the flow ofpressure fluid through the lower delivery line 29 and thereby delayingreturn movement of the piston 21. To this end the pressure fluid line 43is arranged to permit an unrestricted flow of pressure fluid into theauxiliary cylinder 50 and toward the plunger 35in order to shift thelatter promptly for initiating the down stroke of the tool spindle.Means is provided, however, for

restricting the return or exhausting flow of fluid when the pilot valve44 is shifted to a position as seen in Fig. 2, after the completion of adown stroke of the spindle. To this end a unidirectional flow valve 63is mounted in the line 43 for permitting flow therethrough only in onedirection. An exhaust flow of pressure fluid is thus permitted onlythrough a by-pass line 64 extending around, and having its endsconnected to the line 43 on opposite sides of the unidirectional valve.In the by-pass line 64, is means permitting only a restricted exhaustingfluid flow from the cylinder 50, thereby allowing only a defined slowmovement of the'plunger 35 under the influence of full pressure throughthe line 42 on the auxiliary piston 41. Herein this means is shown as adelayed action valve 65.

Under varying circumstances the length of the period of dwell of thehoning tool will have to be increased or shortened. For this purpose thedelayed action valve 65 is arranged for adjustment to accommodate thenecessary variation. Herein this is accomplished by providing the valvewith a rotary stem 66 (Fig. 3) having in one end an axial bore 61 withwhich communicates a series of radial cylindrical orifices 68 ofgraduated diameters. The stem has a flange 69 on its inner end, and isjournaled in a suitably bored housing 10 in which one end of the bore isenlarged to provide a chamber 12. The inner end of this chamber isfashioned to provide a shoulder 13 against which the flange 69 is insnug suificient to retain the valve stem in any adjusted position. Theouter end of the stem 66 extends through a packing gland 11, and has ahandle 18 by which thestem may be adjusted rotatably by simplemanipulation.

The orifices 68 register one at a time with a port 19 which is boredtransversely in the housing 10 and which provides means for threadedlyreceiving a fitting M by which, the remaining end of the by-pass line isconnected to the housing. Thus, it will be seen that as the respectiveorifices 68 are brought into register with the port 19, the exhaustingflow of fluid through the valve will be directly proportionate to thesize of the active orifice. Thereby accurate control may be had over thelength of time requiredfor comthe valve plunger 35 to shift. If desired,an imperforate segment 80 may be left between two of the orifices 68 sothat the user may drill a suitable oriflce therein to provide for agiven period of delayed action that may not have been contemplated atthe time the machine was orig inally assembled.

In operation the motor 22 and the pump 33 are operated'continuously, andafter the cylinder 51 of the work piece has been adjusted upon the worksupport l3, the operator by movement of the lever 23 sets into operationthe mechanism for rotating the spindle. and closes the'cut-out valve 40.Pressure fluid is forced through the feed line 30 into the auxiliaryline 43 to move the control valve plunger 35 to the ieft, as seen inFig. 2, so as to expose the port; upper delivery line. 28, thusinitiating the recipleading to the rocal cycle of the tool spindle l1.When the 75 stroking arm 55 engages the stop 5, it moves the stopmechanism 5| and shifts the pilot valve H to reverse the flow ofpressure fluid through the auxiliary hydraulic systemtby effectingpressure fluid connection between the branch line and the line 42.

Preferably, the stop 54 is arranged to be engaged by the stroking arm ashort time before the stop arm abutments 62 strike the shoulders 58, sothat the enlarged diameter portions Hand 38 of the control valve plungerwill begin to move across the ports leading td the delivery lines 28 and29, before the downward movement of the honing tool is halted, and at arate determined by the delayed action valve 65. In this manner pressurefluid exhausted through the. lower delivery line 29 and the deliverypassage of fluid to the upper delivery line 28 will be cut-off bygradual degrees until 'the stop arm abutments strike the shoulders 58,thereby gradually bringing the spindle to a halt and cushioning themechanism against concussion which would otherwise result between theshoulders and the stop abutments.

As the enlarged portions 31 and 38 of the control valve plunger moveentirely across the ports of the delivery lines 28 and 29 as seen inFig. 2, the flow of pressure fluid to or from the reciprocating cylinder25 is entirely halted so that the honing tool l5 will remain incontinuously r01 tating operative contact for a defined interval withthe wall of the cylinder 51 near its blind end. By properlyproportioning the duration of the dwell, therefore, the metal removedfrom the inner end of the cylinder wall during the dwell will compensatefor that removed from the remaining portions of the cylinder wall duringthe full stroking movement of the tool in engagement therewith. As aresult, diametrically opposite sides of the cylinder wall will be insubstantially perfect parallelism throughout.

As soon as the plunger 35 has been moved sufficiently to open the portof the delivery line 29, the return stroke of the tool spindle will beinitiated, and the return movement will continue until the stroking arm55 strikes the stop 53. 'I'hereupon the pilot valve M will be shiftedagain, and the. reciprocal movement of the spindle reversed in arepetition of the operation just described. When the machine is to bestopped,

, the skip-stop 53 will be moved out of the path of the stroking arm andthe honing tool will be carried away from the work piece a distancedetermined by engagement of the arm with the upper limit stop 52;

From the foregoing, it will be observed that the present inventionprovides an improved automatically operating honing machine for truingand finishing the bores of obstructed or blind end cylinders. Themachine embodies a novel cooperative arrangement of positive stop anddelayed action control mechanism for halting the honing tool at apredetermined point within the cylinder bore short of the blind orobstructed end and for retaining the same in rotary engagement at suchpoint for a definite period calculated to compensate for the'restrictedstroking action of the tool on the portion of the cylinder wall adjacentsaid end as compared with its action on the remainder of the wallsThrough this novel arrangement and relationship of parts and accurateadjustment of the control mechanism operation of the machine is soeifected that the honing tool will remove metal substantially equallyper unit area uniformly throughout the cylinder bore.

By blind and cylinder is meant a cylindrical bore containing anyobstruction which prevents movement of the honing tool entirelytherethrough, such as a closure or flange at one end of the bore, ashoulder as encountered in integral concentric bores, or the like, theblind end being that partof the cylinder construction which causesrestriction of the reciprocal stroke of the tool.

I claim as my invention:

1. A honing machine for truing the bores of blind ,end cylinders ofinternal combustion engines or the like, comprising, in combination,means for supporting a work piece having a blind end cylinder to behoned, a honing tool, operating means including a rotary andreciprocatory tool spindle supporting said-honing tool in position forinsertion into said cylinder, actuating means for imparting reciprocalmotion to said spindle, means for rotating said spindle continuouslywhile the tool is in the cylinder, means for operating said actuatingmeans including a hydraulic system embodying a pilot valve, means forcontrolling said pilot valve including reciprocal cycle defining stopmechanism operable as an incident to the attainment of oppositereciprocal limits by said tool spindle, limiting means for positivelyhalting insertion of said tool into the work beyond a predeterminedpoint short of the blind end of the cylinder, a member engageable withand serving to move said stop mechanism and operate said pilot valvecommencing at a predetermined point prior to halting of the tool by saidlimiting means, and means in said hydraulic system including anadjustable delayed action valve for delaying operatiomof sage: systemand thereby of said actuating means a r said limiting means hashaltedinsertion of the tool, whereby initiation of the return movementof said tool is delayed while it continues rotating in the work.

-2. Ahoning machine for truing the bores of blind end cylinders ofinternal combustion engines or the like, comprising, in combination,means for supporting a work piece to be honed, a honing tool, operatingmeans including a rotary and reciprocatory tool spindle supporting saidhoning tool in position for operating upon the work piece, a, hydrauliccylinder and piston arrangement for i parting reciprocal motion to saidspindle,

means for rotating said spindle continuously while the tool is inoperative association with the work piece, a control valve for definingthe flow direction of pressure fluid to said cylinder, means foroperating said control valve including a hydraulic system embodying apilot valve, means for controlling said pilot valve including reciprocalcycle defining stop mechanism operable as an incident to the attainmentof opposite operative limits of the reciprocal cycle of said spindle,stop means connected with saidspindle serving positively to haltinsertion of said tool into the work beyond a predetermined point at oneoi. said reciprocalv cylinder in said one cycle limit, whereby themovement of said piston is delayed during the last part of the insertingstroke and the return stroke 7 is delayed while said tool continuesrotating in defined working cycle, stop means including a part connectedto said spindle for positively halting approaching movement of thespindle and tool relative to the work near one limit of said workingcycle, operating means controlled by said part for initiating the returnmovement of said working cycle, and means cooperative with said'operating means, for restraining said return movement throughout adefined interval.

4. A honing machine of the character described, comprising, incombination, means for supporting a work piece to be honed, a honingtool, means including a rotary and reciprocatory tool spindle supportingthe tool in position for operating upon the work piece, a hydrauliccylinder and piston arranged for imparting reciprocal motion to saidspindle, a hydraulic circuit connectedwith said cylinder for alternatelydelivering pressure fluid to opposite sides of said piston' to cause thereoeiprocatory niotion of said spindle, positive stop means forinterrupting the movement of said spindle and tool at a predeterminedpoint near onelimit of said reciprocal motion, means in said circuit tocontrol movement of said piston for slowing movement of said-spindleprior to operation of said stop means, and means coacting with said toolspindle for operating said last-mentioned means, whereby the stop meansis brought, into operation by a gradual movement and jarring of themachine is prevented.

' 5. A honingv machine or the character described, comprising, incombination, means for supporting a work piece having a blind endcylinder, tov be honed, a honing tool, means including a rotaryand-reciprocatory tool spindle supporting the tool in position foroperating upon the work piece, means for imparting reciprocal motion tosaid spindle, means for continuously rotating said tool while in honingposition within the cylinder, positive depth stop means for interruptingthe movement of said spindle and tool at a predetermined point short ofthe blind end of said cylinder, said stop means including a cross armattached to said spindle with parts extending laterally of the spindle,adjustable means on each of said parts, and stationary abutmentsadjacent said spindle and engageable by said adjustable means.

6. A honing machine for truing the bores of blind end cylinders,comprising, in combination, a rotary and reciprocating honing tool,means for continuously rotating said tool, hydraulically operated meansincluding a cylinder and piston arrangement for imparting reciprocalforward and return stroking motion to said spindle, a

said auxiliary hydraulic circuit being arranged to deliver anuninterrupted rapid flow of pressure fluid to shift said main controlvalve immediately when'said spindle has reached the limit of its returnstroke, and a manually adjustable delayed action valve in said auxiliarycircuit for delaying operation of said control valve in initiating theflow of pressure fluid through said main circuit to cause the returnstroke of said piston and spindle, whereby said tool will remain inoperation upon a given area of the wall of a cylinder bore for adefined-interval between the'forward and return strokes.

7. In a honing machine for truing the bores of blind end cylinders, thecombination of a respin'dle, control means 'forgoverning operation ofsaid actuating means and including a hydraulic circuit having twobranches, a pilot valve for alternately directing the flow of pressurefluid through said branches, one of said branches having aunidirectional valve permitting rapid flow to said control means butpreventing reverse flow through said branch, a by-pass line connected atits opposite ends on opposite sides of said unidirectional, flow valve,and an adjustable delayed action valve in said by-pass line forrestricting the reverse flow of. fluid around said unidirectional valveat a predetermined rate so as to delay action of said control means andthereby cause a dwell in the movement of said spindle.

, 8. In a honingmachine for truing the bore of blind end cylinders, thecombination of-=a reciprocating tool carrier, a honing tool supported bysaid carrier, hydraulic means for reciprocating said carrier through acycle including forward and return strokes, a control valve forcontrolling operation of said hydraulic means, said valve including areciprocal plunger having opposed actuating pistons, a hydraulic circuithaving branches for delivering pressure fluid to said pistons, a pilotvalve for alternately directing the flow of pressure through saidbranches, one of said branches having a unidirectional valve permittingfluid flow toward said control valve but preventing return flow throughsaid branch, a by-pa'ss line connected at opposite ends on oppositesides of said unidirectional flow valve, and an adjustable delayedaction valve in said line allowing a return flow of fluid around saidunidirectional valve at a predetermined restricted rate so asto delayaction of said plunger for a given time. and thereby cause a dwellbetween the forward and return strokes of said carrier.

9. A honing machine of the character described, comprising, incombination, means for supporting a work piece having a bore to behoned, a honing tool, means including a rotary and reciprocatory toolcarrier/supporting said tool in position for insertion into said bore,means for imparting reciprocal motion of a defined range to saidcarrier, rotary motion mechanism for uninterruptedly rotating saidcarrier while the tool is in operation in said range, positive stopmeans including relatively movable parts coacting with said carrier forinterrupting the reciprocal movement of said carrier and tool at apredetermined point near one end of said range while permittinguninterrupted rotation of said tool, means for cushioning said movableelements againstconcussion to prevent jarring of the machine, and meansoperated by said stop means for effecting operation of said means forcushioning. n

10. In a honing machine for truing the bores of blind end cylinders,thecombination of a reciprocating spindle carrying a rotary honing tool,

hydraulic means for reciprocating said spindle, means for defining thelimit of insertion of the tool into a cylinder bore having a blind end.a hydraulic circuit including a control valve for controlling thereciprocal movements of said spindle, and adelayed-action valve in saidcir-' cuit operable as an incident to the movement of said honing toolto said limit of insertion for delaying operation of said control valveand causing a dwell in the reciprocal movement oi. the tool, saiddelayed-action valve including a bored rotary stem having a plurality ofgraduated orifices and being manually-adjustable to place any selectedorifice into registration in said circuit for determining accurately theperiod of said alternate operations of said control valve forintroducing a dwell in the movement: oi. said one support, said delayedaction valve including a valve member having a plurality 01 graduatedorifices, and means for adjusting the position of said member to rendersaid orifices eflective selectively to determine the length of saiddwell.

1,2. In a honing machine, in combination, a

support for a work piece to be honed, a honing tool, a spindle forsupporting said tool, means for rotating said spindle, means forreciprocating the spindle through a working cycle including approach andreturn movements whereby the rotating tool is traversed over the surfaceof the work piece, limit means for positively halting the approachingmovement 01' the spindle near one limit 01' said working cyclecomprising a stationary part and a member connected for movement withsaid spindle and engageable with said stationary part, and a controldevice including a part also engageable by said member for initiatingthe return movement of the spindle.

13. In a machine for honing cylindrical surfaces, in combination, asupport for work to be honed, a support for a honing tool, means forefi'ecting relative rotation of the tool and work, means for eflecting arelative longitudinal traverse of the tool and. work includinghydraulically actuated means for advancing and retracting one of saidsupports relative to the other support, positive stop means including amember carried by said one support and engageable with a stationary stopfor interrupting the movement 01 the support 'at a predetermined point,a hydraulic circuit for said hydraulically actuated means, a reversingvalve in said circuit operable to reverse the flow direction of pressurefluid in said circuit whereby to control the direction or movement ofsaid one support, hydraulic means including cylinder and pistonmechanism for operating said reversing valve, pressure fiuid supply anddischarge circuits for said cylinder mechanism, a pilot valve, meansactuatedby said member in response to the movements of said onesupportior operating said pilot valve to efl'ect alternate reversals ofthe connection of said supply and discharge circuits to said cylindermechanism to operate said reversing valve, and a manually adjustabledelayed action valve in said discharge circuit operative to throttle thedischarge of fluid from the cylinder mechanism to delay the operation ofsaid reversing valve and thereby cause a dwell in the movement of saidone support so that the tool will remain in operation upon a given areaof the work for a variable predetermined interval.

FLOYD A. SWANSON.

